How to make particles stick to mesh when Molecular Script is enabled?
I maybe have solved it using particles in the lower cubes, and particle linking on collision while simulating everything with molecular. Check the provided blend for more
details. (there is a text file inside, with a few small hints) 

Short version: Cube particles are linked on birth, and also perform linking on collision with nearby plane particles.

Note, the particle linking may slow down the simulation.